500 research outputs found

    Determining the Neutrino Mass Hierarchy with Atmospheric Neutrinos

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    The possibility to determine the type of neutrino mass hierarchy by studying atmospheric neutrino oscillations with a detector capable to distinguish between neutrino and antineutrino events, such as magnetized iron calorimeters, is considered. We discuss how the ability to distinguish between the neutrino mass spectrum with normal and inverted hierarchy depends on detector characteristics like neutrino energy and direction resolutions or charge miss-identification, and on the systematical uncertainties related to the atmospheric neutrino fluxes. We show also how the neutrino mass hierarchy determination depends on the true values of θ13\theta_{13} and θ23\theta_{23}, as well as on the type of the true hierarchy. We find that for μ\mu-like events, an accurate reconstruction of the energy and direction of the neutrino greatly improves the sensitivity to the type of neutrino mass spectrum. For sin22θ130.1\sin^22\theta_{13} \cong 0.1 and a precision of 5% in the reconstruction of the neutrino energy and 55^\circ in the neutrino direction, the type of neutrino mass hierarchy can be identified at the 2σ\sigma C.L. with approximately 200 events. For resolutions of 15% for the neutrino energy and 1515^\circ for the neutrino direction roughly one order of magnitude larger event numbers are required. For a detector capable to distinguish between νe\nu_e and νˉe\bar\nu_e induced events the requirements on energy and direction resolutions are, in general, less demanding than for a detector with muon charge identification.Comment: 24 pages, 8 figure

    A 4-neutrino model with a Higgs triplet

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    We take as a starting point the Gelmini -- Roncadelli model enlarged by a term with explicit lepton number violation in the Higgs potential and add a neutrino singlet field coupled via a scalar doublet to the usual leptons. This scenario allows us to take into account all three present indications in favour of neutrino oscillations provided by the solar, atmospheric and LSND neutrino oscillation experiments. Furthermore, it suggests a model which reproduces naturally one of the two 4-neutrino mass spectra favoured by the data. In this model the solar neutrino problem is solved by large mixing MSW \nu_e\to\nu_\tau transitions and the atmospheric neutrino problem by transitions of \nu_\mu into a sterile neutrino.Comment: Latex, 14 pages, no figure

    How sensitive is a neutrino factory to the angle θ13\theta_{13}?

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    We consider the impact of non-standard interactions of neutrinos (NSI) on the determination of neutrino mixing parameters at a neutrino factory using \pnu{e}\to\pnu{\mu} ``golden channels'' for the measurement of θ13\theta_{13}. We show how a small residual NSI leads to a drastic loss in sensitivity in θ13\theta_{13}, of up to two orders of magnitude. This can be somewhat overcome if two baselines are combined.Comment: 4 pages, 3 figure

    Physics potential of the CERN-MEMPHYS neutrino oscillation project

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    We consider the physics potential of CERN based neutrino oscillation experiments consisting of a Beta Beam (BB) and a Super Beam (SPL) sending neutrinos to MEMPHYS, a 440 kt water \v{C}erenkov detector at Frejus, at a distance of 130 km from CERN. The θ13\theta_{13} discovery reach and the sensitivity to CP violation are investigated, including a detailed discussion of parameter degeneracies and systematical errors. For SPL sensitivities similar to the ones of the phase II of the T2K experiment (T2HK) are obtained, whereas the BB may reach significantly better sensitivities, depending on the achieved number of total ion decays. The results for the CERN-MEMPHYS experiments are less affected by systematical uncertainties than T2HK. We point out that by a combination of data from BB and SPL a measurement with antineutrinos is not necessary and hence the same physics results can be obtained within about half of the measurement time compared to one single experiment. Furthermore, it is shown how including data from atmospheric neutrinos in the MEMPHYS detector allows to resolve parameter degeneracies and, in particular, provides sensitivity to the neutrino mass hierarchy and the octant of θ23\theta_{23}.Comment: 32 pages, 17 figures, minor improvements on the text wrt to v2, version to appear in JHE